U.S. patent application number 13/220294 was filed with the patent office on 2012-03-29 for ball-spline with rotary mechanism.
This patent application is currently assigned to NIPPON THOMPSON CO., LTD.. Invention is credited to Toyohisa ISHIHARA, Shinji KANOH.
Application Number | 20120076447 13/220294 |
Document ID | / |
Family ID | 45870749 |
Filed Date | 2012-03-29 |
United States Patent
Application |
20120076447 |
Kind Code |
A1 |
ISHIHARA; Toyohisa ; et
al. |
March 29, 2012 |
BALL-SPLINE WITH ROTARY MECHANISM
Abstract
A ball-spline with rotary mechanism is provided which is as
small as possible in size, able to perform high-precision works on
a small scale and also weighs less than ever, helping the
downsizing of the component-placement systems. The ball-spline has
a spline shaft, a slider movable along the spline shaft through
balls, and bearings installed on the opposite ends of the slider
for rotation relative to a machine bed. The holder has a pair of
projections which extend through slots in the spacer parts and
slots in the end-cap major body to fit into slots in a carriage.
Fastening screws fit into threaded holes in the projections to
fasten the holder to the opposite ends of the slider.
Inventors: |
ISHIHARA; Toyohisa;
(Gifu-ken, JP) ; KANOH; Shinji; (Gifu-ken,
JP) |
Assignee: |
NIPPON THOMPSON CO., LTD.
Tokyo
JP
|
Family ID: |
45870749 |
Appl. No.: |
13/220294 |
Filed: |
August 29, 2011 |
Current U.S.
Class: |
384/43 |
Current CPC
Class: |
F16C 29/0695
20130101 |
Class at
Publication: |
384/43 |
International
Class: |
F16C 29/06 20060101
F16C029/06 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 29, 2010 |
JP |
2010-218592 |
Claims
1. A ball-spline with rotary mechanism, comprising; an elongated
spline shaft circular in transverse section having raceway grooves
extending lengthwise of the spline shaft on a circular surface of
the shaft at locations angularly opposite to each other, a slider
fitting over or conforming to the spline shaft to move up and down
along the spline shaft in a sliding manner by virtue of rolling
elements of balls, holders lying on lengthwise opposite ends of the
slider, and rolling-contact bearings installed to keep the holders
for rotation relative to a machine bed; wherein the slider is
composed of a carriage of a cylindrical shell having raceway
grooves on an inside circular surface thereof in opposition to the
raceway grooves on the spline shaft to define load-carrying races
between the raceway grooves on the spline shaft and the raceway
grooves on the carriage and further having return passages
extending in parallel with the load-carrying races, end caps
attached to lengthwise opposite ends of the carriage, the end caps
having turnaround passages to connect the load-carrying races with
the return passages, and the balls recirculating through a looped
circuit made up of the load-carrying races, return passages and the
turnaround passages; wherein the carriage has a pair of first slots
extending lengthwise of the carriage on the inside circular surface
at circularly opposite locations in symmetry with each other and
the end caps have paired second slots extending lengthwise of the
end caps on inside circular surfaces thereof to communicate with
the first slots; and wherein the holders each have a flanged
portion adjacent to the end of the slider, a pair of projections
extending integrally from an end surface of the flanged portion to
fit into the first slots in the carriage across the second slots in
one of the end caps, and a bearing mounting of a cylinder formed
integral with the flanged portion to extend from another end
surface opposite to the end surface of the flanged portion to fit
snugly into an inner ring of one of the rolling-contact
bearings.
2. A ball-spline with rotary mechanism as set forth in claim 1,
wherein the projections on one of the holders each include a first
portion to fit into the first slot and a second portion to fit into
the second slot and a gap lying at a boundary between the first
portion and the second portion to provide a stepwise edge which is
envisaged coming into abutment against one of the lengthwise
opposite ends of the carriage, locating in place the holder with
respect to one of the lengthwise opposite ends of the slider to
fasten the holder to the slider.
3. A ball-spline with rotary mechanism as set forth in claim 1,
wherein a pair of the sliders fits over the spline shaft in
lengthwise opposition to each other in a relation spaced at a
preselected interval from each other, a cylindrical collar
interposed between the sliders is fixed to inward ends of the
sliders, the holders having the rolling-contact bearings fit over
outward ends of the sliders, the cylindrical collar on lengthwise
opposite ends thereof being formed with projections identical in
construction with the projections of the holders, and the
projections, after inserted into the first slots in the carriage,
are clamped to the sliders.
4. A ball-spline with rotary mechanism as set forth in claim 1,
wherein at least one of the holders has a cylindrical portion
integral with the bearing mounting and having mounted thereon
rotary driving part for sliding movement relative to the spline
shaft.
5. A ball-spline with rotary mechanism as set forth in claim 1,
wherein the projections of the holders have threaded holes at areas
lying in opposition to threaded holes in the first slots inside the
carriage, so that fastening screws, after having stretched through
the threaded holes in the carriage, fit into the threaded holes in
the projections to fasten the holders to the carriage.
6. A ball-spline with rotary mechanism as set forth in claim 1,
wherein the first slots are formed with the help of unused areas
there is none of the raceway grooves, the return passages and
threaded holes used to fasten the carriage to the end caps.
7. A ball-spline with rotary mechanism as set forth in claim 1,
wherein the end caps are each constituted with a spacer part
attached to one of the end surfaces of the carriage and provided
therein with inside curved halves of the turnaround passages, and
an end-cap major body secured on an outward surface of the spacer
part in adjacent to the flanged portion of the holder and provided
therein with outside curved halves of the turnaround passages.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a ball-spline with rotary
mechanism, which is better for a component-placement head to be
used in an upright or vertical posture in a diversity of
manufacturing machines including, for example, semiconductor
fabricating equipment, assembling machines and so on.
BACKGROUND OF THE INVENTION
[0002] Recently advanced electronics are increasingly required to
be more miniaturized or downsized with high performance.
Correspondingly, the ball-splines with rotary mechanism used as the
component-placement heads in diverse industrial fields including
semiconductor fabricating equipment, assembling machines and so are
also challenged to help the downsizing of the electronics with high
performance.
[0003] In Japanese Laid-Open Patent Application No. 2004-128 485,
there is described an example of the ball-spline with rotary
mechanism, which is used for the component-placement head. With the
prior ball-spline with rotary mechanism, a pair of first and second
sliders is installed on a spline shaft, spaced away at a
preselected interval from each other. The spline shaft is allowed
to travel up and down relatively to the sliders by virtue of
rolling elements or balls. With the prior ball-spline with rotary
mechanism, moreover, there are provided bearing mountings one of
which is installed above the first slider and another mounting is
below the second slider. Cylindrical members are provided one of
which fits over the first slider while another embraces around the
second slider. An intermediate cylindrical member is provided which
extends across the first and second sliders to fit over both the
sliders and connect integrally the sliders with each other. Thus,
the cylindrical members are integrally supported by means of the
bearings for rotation around the lengthwise center of the spline
shaft with respect to a head frame.
[0004] With the ball-spline with rotary mechanism built in the
component-placement head, the cylindrical members have the beating
mountings near the sliders, respectively, which fit snugly into the
cylindrical members. The bearings that have fit over bearing
mountings are slightly larger in outside diameter than the
cylindrical members and therefore the bearings around outer
circular surfaces of their outer rings closely fit into the head
frame to bear the ball-spline for rotation with respect to the head
frame. Thus, the prior ball-spline with rotary mechanism
constructed as stated earlier couldn't get out of becoming bigger
in the outermost diameter by as twice as the radial thickness of
the cylinder member that has fit over the relevant slider. This
means the prior art is inevitably disadvantageous to downsizing the
ball-spline with rotary mechanism. Moreover, the cylindrical
members have to be worked or finely finished over the inside
circular surface thereof so as to closely fit over the outside
circular surface of the relevant slider. This also means the prior
construction as stated earlier involves additional manufacturing
steps for ensuring high precision in assemblage.
[0005] Referring to FIG. 8, there is shown a conventional
ball-spline which is mainly composed of a spline shaft 51 of right
circular cylinder having raceway grooves 56 lying diametrically
opposed to each other on a circular surface of the cylinder to
extend lengthwise of the cylinder, and a slider 52 that fits over
or conforms to the spline shaft 51 so as to travel up and down
along the spline shaft 51 in a sliding manner by virtue of rolling
elements or ball 57. The slider 52 is composed of a carriage 53 of
a cylindrical shell that fits over the spline shaft 51, end caps 54
secured on lengthwise opposite ends of the carriage 53, one to each
end, end seals 55 arranged on outward ends of the end caps 54 to
close an annular clearance between the spline shaft and the slider
52, and a plurality of rolling elements allowed to roll in a
recirculating manner through looped circuits. The carriage 53 has
raceway grooves 61 cut in an inside circular surface thereof in
opposition to the raceway grooves 56 on the spline shaft 51 to
define load-carrying raceways 62 between them, and return passages
58 extending in parallel with the load-carrying raceways 62. The
end caps have turnaround passages to connect the load-carrying
raceways 62 to the return passages 58 to provide the looped
circuits made up of the load-carrying raceways 62, return passages
58 and a pair of the turnaround passages. The end caps 54 and end
seals 55 are secured on the carriage 53 by means of fastening
screws 59. The spline shaft 51 comes into mating with the slider 52
through the rolling elements 57 to provide nearly frictionless
linear sliding motion relatively to each other while allowing
transmitting torque between them simultaneously. The slider 52 on a
circular outside thereof has a key slot 60 into which a key fits to
keep the slider 52 against rotation relative to a machine housing
the slider 52 therein.
[0006] As the advanced electronics become more downsized even with
high performance, the ball-spline with rotary mechanism for the
component-placement heads in diverse industrial fields including
semiconductor fabricating equipment, assembling machines and so on
are needed to be downsized with high performance to help the
miniaturization or downsizing of the component-placement systems
that the ball-spline with rotary mechanism is built in.
SUMMARY OF THE INVENTION
[0007] The present invention has for its primary object to overcome
the major challenge as stated earlier, and to provide a ball-spline
with rotary mechanism that is as small as possible in size and also
weighs less than ever, helping the downsizing of the
component-placement systems that the ball-spline with rotary
mechanism is built in.
[0008] The present invention is concerned with a ball-spline with
rotary mechanism, comprising; an elongated spline shaft circular in
transverse section having raceway grooves extending lengthwise of
the spline shaft on a circular surface of the shaft at locations
angularly opposite to each other, a slider fitting over or
conforming to the spline shaft to move up and down along the spline
shaft in a sliding manner by virtue of rolling elements of balls,
holders lying on lengthwise opposite ends of the slider, and
rolling-contact bearings installed to keep the holders for rotation
relative to a machine bed;
[0009] wherein the slider is composed of a carriage of a
cylindrical shell having raceway grooves on an inside circular
surface thereof in opposition to the raceway grooves on the spline
shaft to define load-carrying races between the raceway grooves on
the spline shaft and the raceway grooves on the carriage and
further having return passages extending in parallel with the
load-carrying races, end caps attached to lengthwise opposite ends
of the carriage, the end caps having turnaround passages to connect
the load-carrying races with the return passages, and the balls
recirculating through a looped circuit made up of the load-carrying
races, return passages and the turnaround passages;
[0010] wherein the carriage has a pair of first slots extending
lengthwise of the carriage on the inside circular surface at
circularly opposite locations in symmetry with each other and the
end caps have paired second slots extending lengthwise of the end
caps on inside circular surfaces thereof to communicate with the
first slots; and
[0011] wherein the holders each have a flanged portion adjacent to
the end of the slider, a pair of projections extending integrally
from an end surface of the flanged portion to fit into the first
slots in the carriage across the second slots in one of the end
caps, and a bearing mounting of a cylinder formed integral with the
flanged portion to extend from another end surface opposite to the
end surface of the flanged portion to fit snugly into an inner ring
of one of the rolling-contact bearings.
[0012] In the present invention, a ball-spline with rotary
mechanism is provided in which the projections on one of the
holders each include a first portion to fit into the first slot and
a second portion to fit into the second slot and a gap lying at a
boundary between the first portion and the second portion to
provide a stepwise edge which is envisaged coming into abutment
against one of the lengthwise opposite ends of the carriage,
locating in place the holder with respect to one of the lengthwise
opposite ends of the slider to fasten the holder to the slider.
[0013] In the present invention, a ball-spline with rotary
mechanism is provided in which a pair of the sliders fits over the
spline shaft in lengthwise opposition to each other in a relation
spaced at a preselected interval from each other, a cylindrical
collar interposed between the sliders is fixed to inward ends of
the sliders, the holders having the rolling-contact bearings fit
over outward ends of the sliders, the cylindrical collar on
lengthwise opposite ends thereof being formed with projections
identical in construction with the projections of the holders, and
the projections, after inserted into the first slots in the
carriage, are clamped to the sliders.
[0014] In the present invention, a ball-spline with rotary
mechanism is provided in which at least one of the holders has a
cylindrical portion integral with the bearing mounting and having
mounted thereon rotary driving part for sliding movement relative
to the spline shaft.
[0015] In the present invention, a ball-spline with rotary
mechanism is provided in which the projections of the holders have
threaded holes at areas lying in opposition to threaded holes in
the first slots inside the carriage, so that fastening screws,
after having stretched through the threaded holes in the carriage,
fit into the threaded holes in the projections to fasten the
holders to the carriage.
[0016] In the present invention, a ball-spline with rotary
mechanism is provided in which the first slots are formed with the
help of unused areas there is none of the raceway grooves, the
return passages and threaded holes used to fasten the carriage to
the end caps.
[0017] In the present invention, a ball-spline with rotary
mechanism is provided in which the end caps are each constituted
with a spacer part attached to one of the end surfaces of the
carriage and provided therein with inside curved halves of the
turnaround passages, and an end-cap major body secured on an
outward surface of the spacer part in adjacent to the flanged
portion of the holder and provided therein with outside curved
halves of the turnaround passages.
Advantageous Effects of the Invention
[0018] In the ball-spline with rotary mechanism constructed as
stated earlier according to the present invention, since the slider
has the slots on the inside circular surface thereof and the
holders to install the bearings at the opposite ends of the slider
have the projections to fit into the slots, there is no need to
mount any other additional component around the slider. Thus, the
ball-spline with rotary mechanism, as being compact or slim in the
overall outside dimension, can be downsized as small as possible
and is adapted to perform high-precision works on a small scale. As
only the complementary fit between the slots and the projections is
sufficient to join the sliders and holders together, there is no
need of high-precision works for complementary fit over wide mating
surfaces and, therefore, the holders are easy for machining works.
Moreover, the complementary fit between the slots inside the slider
and the projections out of the holder is effective in weight
reduction of the overall construction. With the alternative version
of the ball-spline with rotary mechanism in which the collar is
interposed between the sliders, as the collar may be made with a
member less in the outside diameter and, therefore, easy for
machining works. The alternative version is made as small as
possible in size, able to perform high-precision works on a small
scale and also weighs less than ever, helping the downsizing of the
component-placement systems and, therefore, more adapted to the
high-speed machines.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a view in front elevation showing a preferred
embodiment of a ball-spline with rotary mechanism constructed
according to the present invention:
[0020] FIG. 2 is a view in end elevation of the ball-spline with
rotary mechanism of FIG. 1:
[0021] FIG. 3 is an exploded view in perspective to illustrate the
ball-spline with rotary mechanism of FIG. 1:
[0022] FIG. 4 is a view in longitudinal section taken on the plane
of the line IV-IV of FIG. 2:
[0023] FIG. 5 is a view in front elevation showing a second version
of the ball-spline with rotary mechanism according to the present
invention:
[0024] FIG. 6 is a view in end elevation showing a collar in FIG.
5:
[0025] FIG. 7 is a view in longitudinal section of the collar of
FIG. 5, taken on the plane of the line VII-VII of FIG. 6: and
[0026] FIG. 8 is a view in perspective, partially broken away,
showing a conventional ball-spline.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0027] Preferred embodiments of the ball-spline with rotary
mechanism according to the present invention will be explained
hereinafter in detail with reference to the accompanying drawings.
The ball-spline with rotary mechanism of the present invention is
suited for the component-placement head which is envisaged working
in an upright or vertical posture in a diversity of manufacturing
machines including semiconductor fabricating equipment, assembling
machines and so on. More especially, the ball-spline with rotary
mechanism of the present invention features an application of
rolling-contact bearings to the conventional ball-spline working as
the linear motion guide unit, and further an assembling
construction between tubular holders 7, 8 and sliders 2, 2A, 2B to
make it possible to install the rolling-contact bearings 9 10 at
lengthwise opposite ends of the slider 2.
[0028] Referring first to FIGS. 1 to 4, there is shown a preferred
embodiment of the ball-spline with rotary mechanism according to
the present invention. With the ball-spline with rotary mechanism,
the slider 2 is carried on a head frame or machine frame 36 of a
component-placement head in, for example, a pick-and-place machine
for rotation through the rolling-contact bearings 9, 10 and a
spline shaft 1 fits into the slider 2 so as to travel up and down
through a plurality of rolling elements or balls 45 in a sliding
manner with respect to the carried slider 2. Thus, the spline shaft
1 is allowed to rotate while free to travel up and down
simultaneously relative to the head frame or machine frame 36.
After the ball-spline with rotary mechanism has been actuated, a
nozzle head, not shown, at the tip of the spline shaft 1
pneumatically picks up a component or part from a feeder or tray,
rotates the component to the correct orientation and then moves
down towards a preselected location on, for example a printed
circuit board with high precision.
[0029] The ball-spline with rotary mechanism is composed of the
spline shaft 1 circular in transverse section having lengthwise
raceway grooves or first raceway grooves 12 lying on a circular
surface of the shaft 1 at locations diametrically opposite to each
other, the slider 2 allowed to move up and down along the shaft 1
in a sliding manner by virtue of the rolling elements or balls 45,
and the rolling-contact bearings 9, 10 installed with intervention
of the tubular holders 7, 8 on lengthwise opposite ends of the
slider 2. The slider 2 is provided on an inside circular surface
thereof with lengthwise slots 21, 22 and 23 while the tubular
holders 7, 8 to be intervened between the ends of the slider 2 and
the rolling-contact bearings 9, 10 have projections 20 which are
formed to snugly fit into the slots 21, 22 and 23. Mating
engagement between the projections 20 and the slots 21, 22 and 23
complement each other contributes to the provision of the
ball-spline with rotary mechanism compact in construction as a
whole and less in weight.
[0030] The rotary mechanism combined with the ball-spline is
constituted with the rolling-contact bearings 9, 10 installed at
the lengthwise opposite ends of the slider 2 in the ball-spline in
which the slider 2 fits over the spline shaft 1 to travel up and
down the shaft 1 in a sliding manner. The ball-spline with rotary
mechanism of the present invention is shrunk in overall dimension,
for instance, an outside diameter of the spline shaft 1: 5 mm, an
outside diameter of the slider 2: 9.9 mm, and the rolling-contact
bearings 9, 10 are miniature ball bearings having the dimensions of
an inside diameter: 7 mm, an outside diameter: 11 mm, and an axial
length: 3 mm.
[0031] The slider 2 as shown in FIGS. 1 to 3 is composed of a
carriage 3 of a cylindrical shell that fits over the spline shaft 1
for sliding movement relative to the spline shaft 1, the carriage 3
having lengthwise raceway grooves or second raceway grooves 24 in
opposition to the first raceway grooves 12 cut on the spline shaft
1, and end caps 4 attached to lengthwise opposite ends of the
carriage 3, one to each end, the end caps 4 having spacer parts 6
lying on end surfaces 29 of the carriage 3 and end-cap major bodies
5 combined in close contact and in axial alignment with the spacer
parts 6. On the lengthwise opposite ends of the slider 2, there are
provided the rolling-contact bearings 9, 10 with intervention of
the tubular holders 7, 8 in such a relation that the bearing 9, 10
are raised a little in a radial direction above the outside
diameter of the slider 2. The rolling-contact bearings 9, 10 are
composed of inner rings 15 mounted on shoulders 33 of the tubular
holders 7, 8, outer rings 14 surrounding the inner rings 15 for
rotation relative to each other and kept in place inside the
machine frame, and the rolling elements 16 interposed between the
outer ring 15 and the inner ring 14. With the embodiment discussed
here, the outer rings 14 of the rolling-contact bearings 9, 10 each
have a radial dimension raised slightly above the outside diameter
of the slider 2, and the tubular holders 7, 8 are secured to the
slider 2. The tubular holders 7, 8 have inside circular surfaces
which are isolated away from the spline shaft 1 so as not to touch
the spline shaft 1 as in the inside circular surface of the slider
2. The tubular holders 7, 8 each have a flanged portion 13
identical in an outside diameter with the slider 2, a bearing
mounting 31 adjacent to the flanged portion 13, and a collar
extending towards the slider 2 from an end opposite to the flanged
portion 13.
[0032] The ball-spline with rotary mechanism constructed according
to the first embodiment as stated earlier is envisaged having been
employed in the pick-and-placement head. The tubular holder 7 laid
on one side, left in FIG. 1, of the slider 2 has a cylindrical
portion 19 which is to have a gear wheel thereon and terminates to
external threads 32. Thus, the cylindrical portion 19 has mounted
thereon driving parts to transmit the rotary power of a motor, not
shown, to the spline shaft 1 through the tubular holder 7. Another
tubular holder 8 laid on the other side of the slider 2 has only an
axial length sufficient to fit just into the rolling-contact
bearing 10. With the embodiment constructed as stated earlier, the
tubular holders 7, 8 installed on opposite sides of the slider 2
have the respective rolling-contact bearings 9, 10. The slider 2
employed here is of long type having more load-carrying capacity
than in the standard product. The slider 2, as having the carriage
3 longer than in the standard product, makes the raceway grooves 24
in the slider 2 longer than ever and correspondingly making it
possible to increase the number of the rolling elements 45 so as to
carry heavier load. Thus, it is to be understood that the
ball-spline with rotary mechanism of the first embodiment is made
more compact in lengthwise direction, as compared with a
ball-spline with rotary mechanism having a pair of sliders 2A, 2B
as will be stated later.
[0033] Moreover, the tubular holders 7, 8 as shown in an exploded
perspective view of FIG. 3 each have a pair of the projections 20
extending integrally from an end surface of the flanged portion 13
into the interior of the slider 2. The projections 20 each have a
length which falls short of a half the overall axial length of the
carriage 3 so as not to come into hitting against the projections
20 of the counter tubular holder 8. The paired projections 20 on
one of the tubular holders 7, 8 have inside circular surfaces lying
in diametrically opposite relation with each other and extending in
coplanar with the inside circular surface of the flanged portion
13. The projections 20 each have a rectangular configuration in
transverse section and have an outside circular surface which
includes a first distal outside circular surface put deep into the
carriage 3 and a second proximal outside circular surface lying
between the first distal outside circular surface and the outward
end of the flanged portion 13 to be set inside the end cap 4 of the
slider 2. The second proximal outside circular surface is raised
radially above the first distal outside circular surface to provide
a radial gap 34 at a boundary between the first outside surface and
the second outside surface. The radial gap 34 forms a stepwise edge
35 lying in perpendicular to the axial direction of the tubular
holders 7, 8 so as to come into abutment against the relevant end
surface 29 of the carriage 3 after the projections 20 have fitted
deeply into the lengthwise slots 21, 22 and 23. That is, the
outside circular surfaces of the projections 20 of the tubular
holders 7, 8 have the radial gaps 34 serving as the stepwise edges
35 which come into abutment against the end surfaces 29 of the
carriage 3.
[0034] With the tubular holders 7 and 8 constructed as stated
earlier, the outside circular surfaces on the first distal portions
of the projections 20 have threaded holes 28 which are used to
firmly connect the holders 7, 8 to the carriage 3 through fastening
screws 17 tightened from the outside of the carriage 3. On an end
surface of the flanged portion 13 axially opposite to the
projections 20, there is provided the bearing mounting 31 on which
any one of the rolling-contact bearings 9, 10 is mounted. The
bearing mountings 31 are each defined with the end surface of the
flange portion 13 lying perpendicular to the axial direction of the
tubular holder 7 or 8, and the shoulder 33 reduced radially
relative to the flanged portion 13 and extended axially from the
end surface to fit into the inner ring of the rolling-contact
bearing 9 or 10. On the outside circular surfaces of the
projections 20 of the tubular holders 7 and 8, the gaps 34 are
provided at the middle lengthwise of the projections 20. The gaps
34 each have the stepwise edge 35 lying so as to come into abutment
against the end surface 29 of the carriage 3, making certain of
accurate location of the relevant tubular holder 7 or 8. The
provision of the stepwise edges 35 envisaged coming into abutment
or engagement with the end surfaces 29 of the carriage 3 makes it
possible to fasten securely the tubular holders 7, 8 to the end
surfaces of the slider 2 at the preselected locations where there
remain small clearances to keep the flanged portions 13 of the
tubular holders 7, 8 from engaging with or coming collision against
the end surfaces of the end caps 4 of the slider 2.
[0035] The shoulders 33 of the tubular holders 7, 8 each have an
outside diameter identical with an inside diameter of the inner
ring 15 of the rolling-contact bearing 9 or 10 while having an
inside circular surface coplanar with the inside circular surface
of the flanged portion 13 to form a cylinder extending integrally
from the end surface of the flanged portion 13 in an axial
direction of the flanged portion 13. The tubular holder 7 has the
cylindrical portion 19 which is further elongated from the cylinder
of the flanged portion 13 in the axial direction. The cylindrical
portion 19 is to carry a gear wheel thereon and terminates to the
external threads 32. Namely, the tubular holder 7 has the
cylindrical portion 19 which is integral with the shoulder 33 and
has the male threads 32 at the end thereof. Further the cylindrical
portion 19 fits over the spline shaft 1 for free sliding movement
relative to the spline shaft 1 and is equipped thereon with the
rotary parts. Another tubular holder 8 has the shoulder 33 which is
substantially equal in axial length or width to the axial width of
the rolling-contact bearing 10. The shoulders 33 as shown in FIG. 4
each have an outside diameter which is determined to keep such a
relation that the outside circular surface or the outside diameter
of the outer ring of the rolling-contact bearing 9 or 10 mounted on
the shoulder 33 is slightly raised above the outside circular
surface or the outside diameter of the slider 2. With the relation
between the outside circular surfaces of the slider 2 and the
bearings 9, 10 as stated just earlier, the slider 2 is protected
from a possibility of interfering around the outside circular
surface thereof with the machine frame 36 such as the
component-placement heads and so on whenever the slider 2 is
rotated. The end surfaces of the flanged portions 13 confronting to
the bearings 9, 10 as shown in FIG. 4 are at right angles relative
to the lengthwise direction of the slider 2 so as to come into
close engagement with end surfaces of the inner rings 15 of the
bearing 9, 10 which have fitted over the bearing mountings 31 or
shoulders 33, thereby keeping in place the bearings 9, 10. The end
surfaces of the flanged portions 13 are cut relieved around a
circular edge thereof so as not to touch end surfaces of the outer
rings 14 of the bearings 9, 10, thereby allowing the outer rings 14
of the bearings 9, 10 to rotate freely.
[0036] On the inside circular surface of the slider 2, as shown in
FIG. 3, there are provided the lengthwise slots 21, 22 and 23 to
accommodate the projections 20 of the tubular holders 7, 8. The
slider 2 is composed of the carriage 3 of the cylindrical shell in
which the spline shaft 1 fits for sliding movement, the carriage 3
having the second raceway grooves 24 cut in the inside circular
surface thereof in opposition to the first raceway grooves 12 on
the spline shaft 1, the carriage 3 further having return passages
30 extending in parallel with the load-carrying raceways defined
between the first and second raceway grooves 12 and 24, the spacer
parts 6 attached to the end surfaces of the carriage 3, one to each
end surface, and provided therein with inside curved halves 26 of
the turnaround passages to connect the load-carrying races and
their associated return passages 30, and the end-cap major bodies 5
secured on the outward surfaces of the spacer parts 6 and provided
therein with outside curved halves 25 of the turnaround passages.
The end caps 4 are each constituted with a combination of the
end-cap major body 5 and the spacer part 6. The slider 2 of the
present invention is more compact or slim in construction than ever
because of having no end seals as opposed to the conventional
sliders.
[0037] The slots 21, 22 and 23 in the slider 2 are designed to
snugly fit over the projections 20 of the tubular holders 7, 8 and
placed in diametrical opposition (180 degrees) on the inside
circular surface to extend at right angles or 90 degrees relative
to the raceway grooves 24. With the carriage 3, especially, the
slots 21 or the first slots are made with the help of unused areas
there is none of the raceway grooves 24, the return passages 30 and
threaded holes 18. With the end-cap major bodies 3, further, the
slots 22 or the second slots are cut with the help of unused areas
there is none of threaded or cored holes 46 and the raceway grooves
24 and the outside curved halves 25 of the turnaround passages. The
spacer parts 6 has the slots 23 or the third slots which are made
with the help of unused areas there is none of threaded or cored
holes 46 and the inside curved halves 26 of the turnaround
passages. The slots 21 in the carriage 3 have bottoms lying at an
inside diameter in which the first outside circular surfaces of the
projections 2C are allowed to come into mating with the bottoms
after the projections 20 have fitted deeply into the slots 21. The
slots 22, 23 in the end-cap major bodies 5 and the spacer parts 6
for the end caps 4 have bottoms lying at a common inside diameter
in which the second outside circular surfaces of the projections 20
are allowed to come into mating with the bottoms. Moreover, the
slots 22, 23 in the end-cap major bodies 5 and the spacer parts 6
for the end caps 4 are cut deeper than the slots 21 in the carriage
3 by as much as the radial gaps 34 on the projections 20. All the
slots 21 in the carriage 3, slots 22 in the end-cap major bodies 5
and the slots 23 in the spacer parts 6 are in alignment with each
other to allow the projections 20 of the tubular holders 7, 8 to
extend through the slots 21, 22 and 23.
[0038] On the outside circular surface of the carriage 3, a pair of
bolt holes is bored in opposition to the slots 21. Fastening screws
17, after having stretched through the holes, fit into threaded
holes 28 in the projections 20 to fasten the tubular holders 7, 8
to the slider 2. The spline shaft 1 of elongated cylinder has the
raceway grooves 12 lying diametrically opposed to each other on a
circular surface of the cylinder to extend lengthwise of the
cylinder, and an axial through-hole 11 to communicate a pneumatic
suction source to a nozzle head, not shown, which is mounted on the
tip of the spline shaft 1 to pick up and then place components.
[0039] The ball-spline with rotary mechanism of the present
invention is constructed as follows with the components as stated
earlier.
[0040] First, the end caps 4 each composed of the end-cap major
body 5 and the spacer part 6 are secured to the end surfaces 29 of
the carriage 3, one to each end surface, with the fastening screws
27 and at the same time the rolling elements of balls 45 are
charged into the looped or closed circuits to complete the assembly
of the slider 2. Especially, the carriage 3 on the end surfaces 29
thereof has a pair of the threaded holes 18, and the end-cap major
bodies 5 and the spacer parts 6 to form the end caps 4 each have a
pair of the cored holes 46 lying in opposition to the threaded
holes 18 on the carriage 3. Then, after keeping all the carriage 3,
spacer parts 6 and the end-cap major bodies 5 so as to bring their
threaded holes 18 and cored holes 46 into line, the screws 27
stretch through the cored holes 46 when tightened and fit into the
threaded holes 18 to clamp the spacer parts 6 and end-cap major
bodies 5 together with the carriage 3 into the completed slider
2.
[0041] In second phase, the projections 20 of the tubular holders
7, 8 are inserted into the slots 22, 23 and 21 from both the end
surfaces of the slider 2 to a depth the stepwise edges 35 at the
radial gaps 34 on the projections 20 come into abutment against the
end surfaces 29 of the carriage 3. Then, the fastening bolts 17 are
tightened from the outside of the carriage 3 to fit into the
threaded holes 28 in the projections 20 to complete the slider 2
having the tubular holders 7, 8 on the end surfaces thereof. For
more firmly securing together the components stated earlier,
moreover, any adhesives may be applied to mating surfaces of the
carriage 3 with the projections 20 of the tubular holders 7, 8.
[0042] In third phase, the spline shaft 1 fits into the slider 2
together with tubular holders. Then, the shoulder 31 or bearing
mountings 33 are machined on the tubular holders 7, 8 in accurate
concentricity with the spline shaft 1.
[0043] In fourth phase, the rolling-contact bearings 9, 10 are held
securely in place on the shoulder 31 or bearing mountings 31
whereby the ball-spline with rotary mechanism is wrought.
[0044] Referring now to FIGS. 5 to 7, there is shown a second
version of the ball-spline with rotary mechanism according to the
present invention. With the ball-spline with rotary mechanism of
the second version, sliders 2A and 2B are spaced away from each
other at a preselected interval on the spline shaft 1. This version
is preferable to an application in which the tip of the spline
shaft 1 is subject to large momentum of force.
[0045] With the ball-spline with rotary mechanism of the second
version in which the sliders 2A, 2B are opposed to each other on
the spline shaft 1 in a way spaced at a preselected interval from
each other, a cylindrical collar 37 interposed between the sliders
2A, 2B is fixed to inward ends of the sliders 2A, 2B. The tubular
holders 7, 8 having the rolling-contact bearings 9, 10 fit over
outward ends of the sliders 2A, 2B on the opposite side of the
inward ends fastened to the cylindrical collar 37. On lengthwise
opposite ends of the cylindrical collar 37, there are formed
projections 39 like the projections 20 of the tubular holders 7, 8.
The projections 39, after inserted into the slots 21, 22 and 23 in
the sliders 2A and 2B, are clamped to the sliders 2A, 2B by means
of the fastening screws 17 which stretch through the holes in the
carriage 3 and fit into threaded holes 41 in the projections 39 to
fasten the tubular holders 7, 8 to the slider 2.
[0046] As seen in FIG. 5, the ball-spline with rotary mechanism
according to the second version is composed of the sliders 2A, 2B
opposed to each other on the elongated spline shaft 1 while spaced
at a preselected interval from each other, the cylindrical collar
37 interposed between the sliders 2A, 2B and secured to inward ends
of the sliders 2A, 2B, the tubular holder 7 having the
rolling-contact bearing 9 which fits over the outward end of the
slider 2A on the opposite side of the inward end fastened to the
cylindrical collar 37, and the tubular holder 8 having the
rolling-contact bearing 10 which fits over the outward end of the
slider 2B on the opposite side of the inward end fastened to the
cylindrical collar 37. The tubular holders 7 and 8 have the same
construction as in the first version stated earlier. The sliders 2A
and 2b have the same dimension as in the standard product and the
carriage 3 has the same length as in the standard product. Thus,
the sliders 2A and 2B are less in length as compared with the
slider 2 in the first version. The slots 21, 22 and 23 in the
sliders 2A and 2B, namely, the slots 21 or the first slots in the
carriages 3 and the slots 22, 23 in the spacer parts 6 and the
end-cap major bodies 5 for the end caps 4 are constructed as with
the slots in the first version.
[0047] The second version features the distinctive construction of
the collar 37. As shown in FIGS. 6 and 7, the collar 37 includes a
cylindrical major portion 38 of a preselected length extending
between the inward ends of the sliders 2A and 2B opposing to each
other, and a pair of projections 39 extending integrally out of
lengthwise opposite ends of the cylindrical major portion 38. An
inside circumferential surface 44 of the cylindrical major portion
38 merges with the inside circumferential surfaces 44 of the
projections 39 into a common coplanar inside circular surface 44
which extends without coming into touching the spline shaft 1
throughout as in the inside circular surfaces of the tubular
holders 7, 8. The projections 39 of the collar 37 have the same
construction as in the projections 20 of the tubular holders 7, 8
in the first version. The projections 39 have the inside
circumferential surfaces extending in coplanar with the inside
circumferential surface of the cylindrical major portion 38.
Moreover, the projections 39 are placed in diametrical symmetry
with each other or at 180 degrees away from each other. The
projections 39 each have a rectangular configuration in transverse
section perpendicular to the axial direction and have an outside
circular surface sunken radially below an outside circular surface
around the cylindrical major portion 38. The projections 39 each
include a first distal portion to fit deep into the slot 21 in the
carriage 3 and a second proximal portion lying between the distal
portion and the outward end of the cylindrical major portion 38 to
fit into the slots 22, 23 inside the and cap 4 of the slider 2A or
2B. A second outside circular surface on the second proximal
portion is raised radially above a first outside circular surface
on the first distal portion to provide a radial gap 40 at a
boundary between the first outside circular surface and the second
outside circular surface. The radial gap 40 forms a stepwise edge
42 lying in perpendicular to the axial direction of the collar 37
so as to come into abutment against the relevant end surface 29 of
the carriage 3 after the projections 39 have fitted deeply into the
lengthwise slots 21, 22 and 23.
[0048] Namely, the outside circular surfaces of the projections 39
have the radial gaps 40 serving as the stepwise edges 42 which are
envisaged coming into abutment against the end surfaces 29 of the
carriage 3. The stepwise edges 42 at the radial gaps 40 on the
outside surfaces of the projections 39, when the projections 39
have been introduced or inserted into the sliders 2A and 2B, come
into abutment or engagement with the end surface 29 of the carriage
3, making certain of accurate location of the collar 37 at the
preselected location where the collar 37 is fastened to the ends of
the sliders 2A, 2B with remaining small clearances to keep the
lengthwise ends of the cylindrical major portion 38 of the collar
37 away from engaging with or coming collision against the end
surfaces of the end caps 4 of the sliders 2A and 2B. On the outside
circular surfaces on the first distal portions of the projections
39 of the collar 37, there are provided threaded holes 41 which are
used to firmly connect the collar 37 to the sliders 2A, 2B through
fastening screws 17 tightened from the outside of the carriage 3.
The outside circular surface around the cylindrical portion 38 of
the collar 37 is made flush with the outside circular surfaces
around the second proximal portions of the projections 39. Thus,
the projections 39 each have the outside circular surface sunken
radially below the outside circular surface around the cylindrical
major portion 38 of the collar 37.
[0049] The ball-spline with rotary mechanism of the second version
is constructed as follows.
[0050] First, the projections 39 of the collar 37 lying between the
inward end surfaces of the sliders 2A, 2B are inserted into the
slots 22, 23 and 21 of the sliders 2A, 2B to a depth the stepwise
edges 42 at the radial gaps 40 on the projections 39 come into
abutment against the end surfaces 29 of the carriage 3. Then, the
fastening bolts 17 are tightened from the outside of the carriage 3
to fit into the threaded holes 41 in the projections 39 to complete
a tandem slider combined with the collar 37. For more firmly
securing together the components stated earlier, moreover, any
adhesives may be applied to mating surfaces of the carriage 3 with
the projections 39 of the collar 37.
[0051] In second phase, the projections 20 of the tubular holder 7
are introduced into the slots 22, 23 and 21 from an outward end
surface of the slider 2A to a depth the stepwise edges 35 at the
radial gaps 34 on the projections 20 come into abutment against the
end surfaces 29 of the carriage 3. Then, the fastening bolts 17 are
tightened from the outside of the carriage 3 to fit into the
threaded holes 28 in the projections 20 to secure the holder 7 to
the end surface of the slider 2A. The projections 20 of another
tubular holder 8 are inserted into the slots 22, 23 and 21 from an
outward end surface of the slider 2B to a depth the stepwise edges
35 at the radial gaps 34 on the projections 20 come into abutment
against the end surfaces 29 of the carriage 3. Then, the fastening
belts 17 are tightened from the outside of the carriage 3 to fit
into the threaded holes 28 in the projections 20 to secure the
holder 8 to the end surface of the slider 2B to thereby complete
the combined sliders 2A, 2B together with the tubular holders. For
more firmly joining together the sliders 2A, 2B and the tubular
holders 7, 8, moreover, any adhesives may be applied to mating
surfaces of the slots 21 and the projections 21.
[0052] In third phase, the spline shaft 1 fits into the sliders 2A,
2B with the tubular holders. Then, the bearing mountings 31 are
machined on the tubular holders 7, 8 in accurate concentricity with
the spline shaft 1 to provide a ball-spline with the holders having
the concentric bearing mountings 31 thereon.
[0053] In fourth phase, the rolling-contact bearings 9, 10 are held
securely in place on the bearing mountings 31 whereby the
ball-spline with rotary mechanism is wrought according to the
second version.
* * * * *